Electricity 219 



316. An empty house is noisier to walk in and talk in than is a 



furnished one. 



317. Lightning rods are made of metal. 



318. It is harder to hold a frying pan by the end of the handle 



than by part of the handle close to the pan. 



319. Diamonds flash many colors. 



320. In swimming, if you have hold of a fastened rope and try 



to pull it toward you, you go toward it. 



SECTION 35. Complete circuits. 



Why does a doorbell ring when you push a button? 



Why is it that when you touch one electric wire you feel 

 no shock, while if you touch two wires you sometimes get a 

 shock? 



When a wire is broken in an electric light, why does it not 

 light? 



Suppose you have some water in an open circular 

 trough like the one shown in Figure 123. Then suppose 

 you have a paddle and keep pushing the water to your 

 right from one point. The water you push pushes the 

 water next to it, that pushes the water next to it, and so 

 on all around the trough until the water just behind 

 your paddle pushes in toward the paddle; the water 

 goes around and around the trough in a complete cir- 

 cuit. There never is too much water in one place ; you 

 never run out of water. But then suppose a partition 

 is put across the trough somewhere along the circuit. 

 When the water reaches that, it cannot pass ; it has no 

 place to flow to, and the current of water stops. 



The electric circuit. The flow of electricity in an 

 electric circuit may be compared to the How of the v/ater 

 in the tank we have been imagining. The long loop 

 of wire extending out from the dynamo to your house 



